Add PHPStan to integration tests, fix a class name conflict [MAILPOET-2488]

RoboFile.php

@@ -493,6 +493,7 @@ class RoboFile extends \Robo\Tasks {
           "$dir/tests/_support",
           "$dir/tests/DataFactories",
           "$dir/tests/acceptance",
+          "$dir/tests/integration",
           "$dir/tests/unit",
         ])
       )

tasks/phpstan/phpstan-tests.neon

@@ -11,6 +11,7 @@ parameters:
     - ../../tests/_support/_generated # without this line PHPStan segfaults ¯\_(ツ)_/¯
     - ../../tests/_support
     - ../../tests/acceptance
+    - ../../tests/integration
     - ../../tests/unit
   dynamicConstantNames:
     - WP_DEBUG

tests/unit/WooCommerce/TransactionalEmailsUnitTest.php

@@ -10,7 +10,7 @@ use MailPoet\WooCommerce\TransactionalEmails\Renderer;
 use MailPoet\WooCommerce\TransactionalEmails\Template;
 use MailPoet\WP\Functions as WPFunctions;
 
-class TransactionalEmailsTest extends \MailPoetUnitTest {
+class TransactionalEmailsUnitTest extends \MailPoetUnitTest {
 
   public function testGetEmailHeadings() {
     $wp = Stub::make(new WPFunctions, [